This application claims the priority of German Patent Application Serial No. 299 00 250.0, filed Jan. 12, 1999, the subject matter of which is incorporated herein by reference.
The present invention relates to an apparatus for and method of provisionally covering an inspection shaft of an underground duct system during pavement of a surface of a road or square.
Inspection shafts of a subterranean duct system are oftentimes encountered in the area of a surface of a road or square, to be paved with asphalt or concrete. In these situations, the manhole frame including the attached manhole cover are removed from the inspection shaft and the exposed inspection shaft is provisionally covered, before the surface is paved. After removal of the manhole frame and the manhole cover, the upper rim of the inspection shaft is substantially flush with the level of dumped soil on which the asphalt or concrete is laid. The provisional cover prevents soil, asphalt or concrete from dropping into the inspection shaft while yet permitting travel of road-construction vehicles, in particular rollers for compacting the asphalt, concrete or the like, over the inspection shaft.
After pavement of the surface, the rim of the inspection shaft must be cleared again to permit subsequent placement of the manhole frame onto the inspection shaft and connection thereof with the asphalt, concrete or the like, as well as with the rim or, optionally, with a compensation ring, mounted to the inspection shaft for compensating height differences.
Heretofore, the inspection shaft has been provisionally covered during asphalting and concreting by a closed solid plate which has a base area roughly corresponding to the base area of the inspection shaft. During asphalting or concreting, provisions were made to continuously mark the spot of the plate and of the inspection shaft underneath the plate. In this manner, once the surface is fully paved, the plate and the inspection shaft can be cleared again to attach the manhole frame and the manhole cover.
The required marking of the spots of the plate during pavement is very time-consuming and tedious because the provisional marking fails to inform the worker as to the exact location of the center or the edge region of the plate and thus of the inspection shaft. Thus, the fully paved surface must therefore be cleared from asphalt or concrete by hand piece-by-piece in a laborious manner until the edge area of the plate and thus of the inspection shaft becomes visible.
It is thus an object of the present invention to provide an improved apparatus and method for covering an inspection shaft during pavement of a surface of a road or square, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an improved apparatus and method for realizing a trouble-free application of asphalt or concrete over a covered inspection shaft while still allowing easy determination of the precise location of the inspection shaft after the surface has been fully paved.
These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by an apparatus which includes a cover plate formed with a central breakthrough for receiving a pipe for axial displacement therein and including a centering device secured to a bottom side of the cover plate, with the pipe having a centering device distal end face for attachment of a flange, and by providing a detachable lid for closing the pipe.
Through the provision of an apparatus in accordance with the present invention, an inspection shaft can be provisionally covered during asphalting or concreting of a road surface in a cost-saving and time-saving by carrying out the following method steps: Before commencing the actual asphalting or concreting, the cover plate is placed over the inspection shaft and secured by the centering device against lateral displacement relative to the inspection shaft. The pipe is closed by the lid and so inserted in the breakthrough of the cover plate that the flange rests directly on the cover plate. After applying a first layer of asphalt or concrete, the region of the pipe including its flange is easily recognizable by the workman and can be cleared by hand for subsequent removal of the lid. The pipe is then elevated to such an extent that the flange is located above the level of the asphalt course already laid on the surface. In this position, the elevated zone of the pipe and the flange is backfilled with soil, concrete, asphalt or the like so that the flange can be positioned at a level with and supported on the laid course of asphalt or concrete. Thereafter, the pipe is closed again by the lid, which is detachably mounted to the flange, and ready for subsequent application of further layers of asphalt or concrete in a same manner, as described, i.e. after application of each layer, the pipe is elevated accordingly.
In other words, the pipe xe2x80x9cgrowsxe2x80x9d with the thickness of the asphalt or concrete applied and, after applying one layer, can easily be leveled with the layer so as to be easily accessible. This is certainly true also with respect to the top layer of the asphalt or concrete so that the cover plate underneath the finished pavement can be easily and precisely located. Clearing of the cover plate and exposing of the inspection shaft can be rapidly carried out, without tedious search for the boundary of the cover plate as the location of the pipe with its flange and lid can easily be ascertained after application of each layer of the pavement. As only one layer of asphalt or concrete is laid at any time upon the pipe when paving the surface with several courses and the pipe grows with each additional layer, the area of the asphalt or concrete above the lid can be cleared rapidly and easily by a drill as the drill can be centered to the disposition of the pipe. However, even a manual clearance of the cover plate is easy to execute without time-consuming search of the precise location, because the center of the pipe can be utilized as reference point for the area of the cover plate to be cleared.
Suitably, the cover plate, pipe, the flange and lid are each made of metal, such as steel or light metal of sufficient strength and heat-resistant properties.
Elevation of the pipe in concert with each laid asphalt layer is realized by a lifting device which is insertable through the pipe, whereby the pipe has a clear diameter which is so sized as to allow passage of a lifting device through the pipe.
According to another feature of the present invention, the centering device of the cover plate includes several ribs diverging from the breakthrough in star-shaped configuration.
The apparatus for provisionally covering an inspection shaft during asphalting or concreting a road or square, in accordance with the present invention, significantly reduces the time required for the clearance of the inspection shaft, because the top of the pipe as well as the lid can quickly be established so that the location of the cover plate and its center beneath the completed pavement can be precisely ascertained.